The invention relates in general to internal combustion engines, and more particularly to a fuel control system for making such engines more efficient.
Most automobile engines operate on gasoline which is ignited by a spark produced within a combustion chamber. As a consequence these engines require a carburetor to vaporize the gasoline and mix it with air to form a combustible mixture. Carburetors of current manufacture vaporize the gasoline by discharging it through a fuel jet into an airstream passing through a venturi in the carburetor. The orifice in the fuel jet, however, is of fixed diameter, and that diameter represents somewhat of a compromise which permits relatively good operation over a wide range of power settings, but does not provide optimum operation at any power setting. Actually, the orifice of the jet is somewhat oversized for most power demands, so that the compromise favors high power demands, since without the large diameter, the engine would be incapable of developing full power on the few occasions when that is necessary. Also, the oversized jet orifices enable the engine to operate at higher altitudes with little difficulty. Consequently, under most operating conditions, the combustible mixtures supplied to the engines of current manufacture are too rich in gasoline.
Translating the foregoing into the operation of a conventional gasoline powered automobile, under most driving conditions the carburetor supplies more gasoline to the engine than is required to maintain the power for that operating condition. This is particularly true during deceleration when the throttle is released, but the carburetor nevertheless supplies a relatively large charge of gasoline to the engine in view of the large amount of air which is pumped. Also at idling, where the engine requires only enough power to overcome its own internal friction, the gasoline consumed is usually in excess of the amount which is actually necessary to overcome the friction. Even at normal driving speeds the engine receives more fuel than is necessary to maintain such speeds, and the same is true for moderate accelerations to normal driving speeds. Moreover, most vehicles are operated at relatively low altitudes, but the carburetors are designed to operate at higher altitudes as well and, therefore, supply an overly rich air-fuel mixture at the lower altitudes.